MAPT and Alzheimer disease: The transentorhinal region is also prominently affected by tau pathology with NFT accumulation in early idiopathic AD, and additional findings overlap between AD and FTDP-17R406W, including clinical symptoms, expression of all isoforms of tau with laboratory findings of a 3R/4R ratio close to 1, ultrastructural composition of tau in paired helical filaments, with a minority of short filaments [4, 31–35].